Substack’s Growth Engine

Hi I’m Angela 🧸A product growth marketer who exists in the space between caffeine highs and retention lows.

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Lately I’ve had a lot more subscribers from Taiwan, so feel free to interact with me in Mandarin. (最近多了很多台灣訂閱者，可以自由使用中文跟我互動。) : )Today’s piece uses Substack as an example to break down how a product’s growth loops work.Every product needs growth loops, so if you’re curious about how a certain type of product drives user growth, you can reply to this email or leave a comment at the end of the post.

Behavior, Loops, and Funnel Architecture

Most platforms define growth as a race for attention, measured in new signups or viral spikes. Substack followed a different path. Its expansion originated in predictable behavioral patterns between writers and readers. Every feature, every interaction, and every metric reflects the alignment of incentives between these groups.

Substack turns everyday reader habits into creator income： Paid walls, direct emails, and the free-to-paid conversion path make reading feel normal while nudging people to subscribe.

Every click, open, or note reply adds up, moving readers along a predictable path.

Feed economy: How Each Platform Manufactures Dependency Loops

Control comes from the platform: subscription lists, direct access to readers, and ways to turn attention into paying supporters.

This setup keeps Substack’s loops running. Habits create income, income reinforces publishing. Writers keep putting out content, readers keep engaging, and the system compounds trust into stable revenue.

Writing as Funnel Architecture

Every post functions as a step in a behavioral funnel rather than a pure act of expression. Notes, the micro-content layer, operates as a temperature control mechanism. Writers simulate conversation, warming cold readers for future subscription.

Open-ended questions, visibility threads, and staggered calls-to-action modulate the emotional slope between familiar strangers and paying subscribers.

Trust velocity replaces reach as the primary metric. Writers who carefully manage this slope gain compounding returns over time.

A consistent slope from familiar stranger to paying subscriber drives the business.

Mechanics that raise temperature

* Direct email delivery reduces discovery fatigue and slots reading into daily habits.

* Free previews show users why the content is worth paying for exactly when they are looking at it.

* Substack guides users through a series of prompts, starting with gentle suggestions and building up to stronger asks, while nearby examples of other people engaging provide social proof.

* Notes keeps a writer present between big posts, which tightens cadence and shortens time to subscribe.

Calls to action appear in a sequence, from soft ask to hard ask, with social proof embedded at multiple points. When a new reader subscribes, Substack often shows a recommended publications module with numbers or quotes like “Get Angela's recommendations”

People and publications recommended by Angela Zeng,” signaling trust.

Weekly Top Paid or Top Free rankings highlight fast-growing or high-revenue newsletters, giving platform-level endorsement.

Authors often reference or collaborate with other recognized writers, creating an implicit peer approval signal.

At the bottom of articles, comment counts, likes, and highlighted responses show community engagement, reinforcing credibility and nudging new readers toward subscription.

This system fosters a peer-to-peer recommendation environment, allowing creators to support each other's growth and build a community of engaged readers.

From Isolation to Network:

How Substack Turns Writing into a Growth Loop

Most creators quietly fear the same thing: speaking into the void. You can spend months writing, editing, and polishing the perfect newsletter, yet without readers, the work feels like a message in a bottle drifting across an empty ocean.

A few years ago, I started writing on Medium. The topics were similar to what I cover now. After a handf